Many electronic devices are manufactured in a portable form to allow the device to be easily and conveniently used at a variety of locations. Currently, many types of portable electronic devices, such as laptop computers, media playback devices, and global positioning systems employ electromechanical devices such as hard disk drives to store data. The use of hard disk drives with other types of electronic devices, such as mobile telephones, digital cameras, digital camcorders, or the like, is likely to increase in the future.
In addition, many portable electronic devices are being-provided with location systems that allow a location of the portable electronic device to be determined. For example, global-positioning systems (GPS), laptop computers, and cellular telephones are all examples of devices that currently or soon will incorporate both a location system and an electromechanical device such as a hard disk drive (HDD).
The present application is of particular relevance when used in the context of a cellular telephone containing an integral hard disk drive and an integral positioning system, but may be used with portable electronic devices other than cellular telephones and electromechanical devices other than hard disk drives. Accordingly, while various embodiments of the present invention will be described below in the context of a Cellular telephone containing a location system and an integral hard disk drive, the present invention may be embodied in other forms and used in other environments.
Cellular telephones are often exposed to external shocks, such as when the telephone is accidentally dropped onto or banged into a rigid surface such as a floor, wall, door frame, or the like. Solid state electronics in a cellular telephone are relatively resistant to damage from such shocks, but electromechanical devices such as hard disk drives are highly susceptible to damage when subjected to external shocks, especially while operating.
In particular, a conventional hard disk drive comprises one or more disks that are rotated relative to an actuator arm assembly. Each disk defines first and second surfaces on which tracks are defined, with the tracks being radially spaced from the center of the disk. The actuator arm assembly supports a head above each surface of the disk. The actuator arm assembly further radially moves the head relative to the disk to allow the head to be placed above a desired track during read and write operations.
The distance between each head and the disk surface corresponding thereto is referred to as fly height. Ideally, the fly height is a constant, predetermined value. In practice, however, the fly height can vary based on factors such as imperfections on the disk surface. Hard disk drives employ various active and passive mechanisms to control fly height, but these control mechanisms cannot compensate for variations in fly height due to shocks above a predetermined threshold. Accordingly, if a shock on the hard disk drive exceeds the predetermined threshold, the shock may cause the head to come into contact with the surface of the disk, causing damage to the head and/or the disk surface.
On the other hand, most modern hard disk drives define a park mode in which the head is rigidly held against a predetermined portion of the disk surface or unloaded from the disk surface using a ramp. In the past, hard disk drives defined a landing zone on the disk surface, and, when in the park mode, the head is held against the landing zone portion of the disk surface on which data is not stored. However, most modern hard disk drives define a ramp adjacent to the radially innermost portion (or outermost portion) of the disk surface. In this case, the head is unloaded from the disk surface using the ramp and is prevented from being loaded onto the disk surface using, for example, a magnetic latch, when the hard disk drive is in the park mode. In either case, significantly greater shocks can be tolerated without damage to the hard disk drive when the hard disk drive is in the park mode.
If an imminent shock can be detected, shock protection can be provided by placing the hard disk drive into the park mode in advance of the shock. To this end, certain disk drives have been manufactured with an integral motion detector. The motion detector detects motion of the disk drive that indicates that the disk drive has been dropped and thus that a shock is imminent. When motion indicative of imminent shock is detected, the hard disk drive is placed in the park mode to increase the ability of the hard disk drive to resist shocks without damage.
Providing a hard disk drive with an integral shock protection system is not practical or desirable for a number of reasons. One important reason is that an integral shock protection system increases the costs of the hard disk drive. Given that many hard drives may not be used in a manner that requires additional shock protection, computer manufactures do not want to pass the costs of such protection onto every purchaser of a computer containing a hard disk drive. A significant portion of hard disk drives to be manufactured in the future are, thus, likely to be sold without integral shock protection. Further, in the case of a portable electronic device such as a cellular telephone having a positioning system, providing a hard disk drive with an integral shock protection system can result in duplication of hardware.
The need thus exists for improved systems and methods of protecting electromechanical devices used in portable electronic devices from external shocks.